Communications in a medical device system with link quality assessment

ABSTRACT

Methods and devices for testing and configuring implantable medical device systems. A first medical device and a second medical device communicate with one another using test signals configured to provide data related to the quality of the communication signal to facilitate optimization of the communication approach. Some methods may be performed during surgery to implant one of the medical devices to ensure adequate communication availability.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/070,013, filed Mar. 15, 2016, now U.S. Pat. No. 10,213,610, whichclaims the benefit of and priority to U.S. Provisional PatentApplication No. 62/134,726, filed Mar. 18, 2015, the disclosures ofwhich are incorporated herein by reference.

TECHNICAL FIELD

The present disclosure generally relates to medical devices, and moreparticularly to communications between implantable medical devices.

BACKGROUND

Various active implantable devices are available or in development fortreating and/or diagnosing numerous ailments. Some examples includecardiac assist devices, pacemakers, defibrillators, cardiac monitors,neurostimulation and neuromodulation systems, drug and medication pumps,and others. A patient may have multiple implanted devices and maybenefit in some circumstances by enabling such devices to communicatewith one another. Because these implantable devices are generallyreliant on battery power, communication between devices should bedesigned for efficiency and to limit power consumption.

SUMMARY

The present disclosure relates generally to systems and methods formanaging communication strategies using link quality assessment.

A first example is an implantable medical device comprising means forcommunicating by conducted communication with at least a secondimplantable medical device; means for setting the means forcommunicating into a continuing receive mode for analyzing a firstsignal received from the second implantable medical device and a secondsignal received from the second implantable medical device; means foranalyzing the first signal and the second signal as received by themeans for communicating; and means for generating an outputcommunication indicating a result of the analysis of the first signaland the second signal.

A second example takes the form of the implantable medical device of thefirst example, wherein the means for analyzing the first signal and thesecond signal is operable by receiving and analyzing a biological signalfrom a patient to identify events in the biological signal to generate amarker set; and annotating the first signal and the second signal usingthe marker set.

A third example takes the form of the implantable medical device of thesecond example, wherein the biological signal is a cardiac signal andthe events are components of the cardiac cycle.

A fourth example takes the form of the implantable medical device of anyof the first three examples, wherein the continuing receive modeincludes a period for receiving at least one of the first signal and thesecond signal for a duration which exceeds a recurring biological cycleof a patient. A fifth example takes the form of the implantable medicaldevice of the fourth example wherein the recurring biological cycle is acardiac cycle. A sixth example takes the form of the implantable medicaldevice of the fourth example wherein the recurring biological cycle is arespiration cycle.

A seventh example takes the form of the implantable medical device ofany of the first six examples wherein the means for generating an outputcommunication is operable to generate an output communication signaling:a preference for the first signal; a preference for the second signal;or an indication that neither of the first signal nor the second signalis suitable.

An eighth example takes the form of a medical system comprising animplantable medical device as in the seventh example and an externalprogrammer for communication with the implantable medical device, theexternal programmer including a user interface, wherein the implantablemedical device means for generating an output communication is operableto send an output communication for receipt by the external programmer;and wherein the external programmer is configured to indicate to a userif the implantable medical device generated an indication that neitherof the first signal nor the second signal is suitable, and to suggestthat the user modify the position of the implantable medical device.

A ninth example takes the form of a system as in the eighth examplewherein the implantable medical device and external programmer areconfigured to communicate in real-time to indicate to the physicianchanges to a conducted communication signal received by the implantablemedical device as the implantable medical device position is adjusted bythe physician.

A tenth example takes the form of a medical system comprising a firstimplantable medical device as in the seventh example, a secondimplantable medical device, and an external programmer for communicationwith at least one of the first and second implantable medical devices,wherein the first implantable medical device is configured to receivethe first signal and the second signal from the second implantablemedical device and generate the output communication for receipt by thesecond implantable medical device, and the second implantable medicaldevice is configured to communicate to the external programmer.

An eleventh example takes the form of a medical system comprising afirst implantable medical device as in the seventh example and a secondimplantable medical device configured to generate conductedcommunication signals to the first implantable medical device, thesecond implantable medical device comprising at least first, second andthird electrodes for generating the conducted communication to yield atleast first and second conducted communication vectors, wherein thesecond implantable medical device is configured to generate the firstsignal using a first conducted communication vector, and to generate thesecond signal using a second conducted communication vector.

A twelfth example takes the form of a medical system comprising a firstimplantable medical device as in any of the first six examples, a secondimplantable medical device, and an external programmer for communicationwith the first and second implantable medical devices, wherein the firstimplantable medical device is configured to receive the first and secondsignals from the second implantable medical device and generate theoutput communication to the external programmer.

A thirteenth example takes the form of a medical system as in any of thetenth to twelfth examples wherein the first implantable medical deviceis configured as a leadless cardiac pacemaker for implantation entirelywithin the heart of a patient, and the second implantable medical deviceis configured as a subcutaneous-only implantable defibrillator.

A fourteenth example takes the form of the implantable medical device ofany of the first seven examples further comprising therapy circuitry forproviding pacing output and wherein the implantable medical device isconfigured as a leadless cardiac pacemaker for implantation entirelywithin the heart of a patient.

A fifteenth example takes the form of an implantable medical devicecomprising means for communicating by conducted communication with atleast a second implantable medical device, at least first, second andthird electrodes configured for conducted communication with the secondimplantable medical device such that at least first and second conductedcommunication vectors are available for use by the communication means,means for setting the means for communicating to a continuing transmitmode for using the first conducted communication vector to generate anoutput, and then using the second conducted communication vector togenerate an output; means for determining, from information providedback to the implantable medical device, which, if any, of the firstconducted communication vector and second conductive communicationvector is to be used for delivering conducted communication messages tothe second implantable medical device; and means for setting a defaultconducted communication vector for use by the means for communicating.

A sixteenth example is a method of performing a diagnostic test in animplantable medical device system comprising: generating a firstconducted signal from a first medical device intended for receipt by asecond medical device comprising an output pattern for a selectedperiod; receiving the conducted signal by a second medical device andcalculating a parameter of the first conducted signal as received;wherein the selected period exceeds an expected or detected length of arecurring biological cycle.

A seventeenth example takes the form of a method as in the sixteenthexample, wherein the recurring biological cycle is a cardiac cycle. Aneighteenth example takes the form of a method as in the sixteenthexample wherein the recurring biological signal is a respiration cycle.

A nineteenth example takes the form of a method as in any of thesixteenth to eighteenth examples wherein the first medical devicecomprises at least three electrodes configured to output a conductedsignal and the first conducted signal is generated by a firstcombination of electrodes, the method further comprising generating asecond conducted signal using a second combination of electrodes,receiving the second conducted signal and calculating the parameter forthe second conducted signal. A twentieth example takes the form of amethod as in the nineteenth example, further comprising comparing theparameter as calculated for the first conducted signal as received tothe parameter as calculated for the second conducted signal.

A twenty-first example is a method comprising performing a method as inany of the sixteenth to twentieth examples while a patient assumes afirst posture, and repeating the same method while the patient assumes asecond posture.

A twenty-second example is a method of configuring communication betweenimplantable medical devices comprising: in a first implantable devicehaving a plurality of electrodes configured for outputting a conductedsignal, generating a first conducted signal using a selected pair ofelectrodes; in a second implantable device, receiving and analyzing thefirst conducted signal; in the second implantable device, communicatinga second signal related to an outcome of the analysis of the firstconducted signal while the first conducted signal is being received.

A twenty-third example takes the form of a method as in thetwenty-second example, further comprising receiving the second signal inthe first implantable device while the first conducted signal is stillbeing generated. A twenty-fourth example takes the form of a method asin either of the twenty-second or twenty-third examples, wherein thesecond signal is a conducted signal received by the first implantabledevice using a different pair of electrodes than the pair used forgenerating the first conducted signal. A twenty-fifth example takes theform of a method as in either of the twenty-second or twenty-thirdexamples, wherein the second signal is not a conducted signal. Atwenty-sixth example takes the form of a method as in the twenty-secondexample, further comprising receiving the second signal with an externalmedical device configured for communication with at least one of thefirst implantable device and the second implantable device.

A twenty-seventh example is a method of configuring communicationbetween implantable medical devices during an implantation procedure ofa first medical device in a patient in whom a second medical device isalready implanted, the method comprising: during an implantationprocedure for the first medical device, testing communication betweenthe first medical device and the second medical device; determining thatcommunication is suboptimal; and in response to determining thatcommunication is suboptimal, adjusting an orientation of the firstmedical device.

A twenty-eighth example takes the form of a method as in thetwenty-seventh example, wherein at least one of the first medical deviceand the second medical device is configured for communication with anexternal programmer, the method further comprising obtaining a feedbacksignal from the external programmer which indicates in real time aquality of a communication link between the first medical device and thesecond medical device.

A twenty-ninth example takes the form of a method as in either of thetwenty-seventh or twenty-eighth examples wherein the first medicaldevice is a leadless cardiac pacemaker and the second medical device isa subcutaneous implantable cardioverter defibrillator. A thirtiethexample takes the form of a method as in either of the twenty-seventh ortwenty-eighth examples wherein the first medical device is a leadlesscardiac pacemaker (LCP) which is implanted by advancing an implantationcatheter to a desired location and then securing the LCP at the desiredlocation and decoupling the implantation catheter from the LCP, whereinthe step of testing communication is performed while the LCP is coupledto the implantation catheter and before the LCP is secured at thedesired location.

A thirty-first example is a method of operation in an implantablemedical device system comprising an external programmer and firstimplantable medical device and a second implantable medical device, themethod being configured for performance communication quality monitoringduring a procedure to implant the second medical device while the firstmedical device is already implanted, the method comprising: the firstmedical device generating a communication test signal prior tocompletion of placement of the second medical device during theprocedure to implant the second medical device; the second medicaldevice receiving and analyzing the communication test signal from thefirst medical device; the second medical device generating an outputindicating a quality of the communication test signal as received; theprogrammer providing an indication to a physician performing theimplantation procedure related to the quality of the communication testsignal as received by the second medical device.

A thirty-second example takes the form of a method as in thethirty-first example wherein the step of the second medical devicegenerating an output indicating a quality of the communication testsignal comprises the second medical device communicating to theprogrammer in real time, such that the step of the programmer providingan indication is performed in real time. A thirty-third example takesthe form of a method as in the thirty-first example, wherein the step ofthe second medical device generating an output indicating a quality ofthe communication test signal comprises the second medical devicecommunicating back to the first medical device and the first medicaldevice communicating to the programmer to facilitate the programmerproviding the indication to the physician.

A thirty-fourth example takes the form of a method as in any of thethirty-first to thirty-third examples wherein the first and secondmedical devices are each leadless cardiac pacemakers. A thirty-fifthexample takes the form of a method as in any of the thirty-first tothirty-third examples wherein the first medical device is a subcutaneousimplantable cardioverter defibrillator and the second medical device isa leadless cardiac pacemaker.

The above summary is not intended to describe each embodiment or everyimplementation of the present disclosure. Advantages and attainments,together with a more complete understanding of the disclosure, willbecome apparent and appreciated by referring to the followingdescription and claims taken in conjunction with the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosure may be more completely understood in consideration of thefollowing description of various illustrative embodiments in connectionwith the accompanying drawings, in which:

FIG. 1 illustrates a patient having a plurality of implantable medicaldevices;

FIG. 2 illustrates a block diagram of an implantable medical device;

FIGS. 3-5 are diagrams illustrating communications signals relative tobiological signals;

FIG. 6 illustrates a flow diagram and graphic for an illustrativemethod;

FIGS. 7 and 8 are diagrams illustrating communications signals and testsignals relative to biological signals;

FIGS. 9-10 are flow diagrams for illustrative methods;

FIG. 11 is another diagram illustrating communications signals and testsignals relative to biological signals;

FIGS. 12A-12E show programmer screens for an illustrative method;

FIGS. 13A-13B show an implanted system and a detail view of a particulardevice; and

FIGS. 14-16 are flow diagrams for additional embodiments.

While the disclosure is amenable to various modifications andalternative forms, specifics thereof have been shown by way of examplein the drawings and will be described in detail. It should beunderstood, however, that the intention is not to limit aspects of thedisclosure to the particular illustrative embodiments described. On thecontrary, the intention is to cover all modifications, equivalents, andalternatives falling within the spirit and scope of the disclosure.

DESCRIPTION

The following description should be read with reference to the drawingsin which similar elements in different drawings are numbered the same.The description and the drawings, which are not necessarily to scale,depict illustrative embodiments and are not intended to limit the scopeof the disclosure.

FIG. 1 illustrates a patient having a plurality of implantable medicaldevices. A patient, 10 is shown having a leadless cardiac pacemaker(LCP) 14 implanted inside the heart 12. A subcutaneous implantabledefibrillator (SICD) 16 having a left axillary canister and lead 18extending to electrodes 20 is also shown. The patient may also have aninsulin pump 22, a pain pump 24 for delivering pain medication to theshoulder, and/or a nerve stimulator 26 having a lead (not shown)extending to the neck or head.

Other devices could be substituted for those shown in FIG. 1, and thepositions shown for each device are not intended to be limiting. Someadditional or alternative examples include other pacemakers ordefibrillators, such as those with transvenous, intracardiac,epicardial, or substernal electrodes, for example, a cardiac monitor,left ventricular assist device, spinal cord stimulator, vagus nervestimulator, gastric electric stimulator, sacral nerve stimulator, and/orany other implantable medical device.

These various systems may be interrogated by an external device or a“programmer” 28, which may optionally use one or more skin electrodes 30to assist with communication to an implanted device. Skin electrodes 30may be used for conducted communication with an implantable device. Asused herein, conducted communication is communication via electricalsignals which propagate via patient tissue and are generated by more orless ordinary electrodes. By using the existing electrodes, conductedcommunication does not rely on an antenna and an oscillator/resonantcircuit having a tuned center frequency common to both transmitter andreceiver.

For other communication approaches such as RF or inductivecommunication, the programmer 28 may instead use a programming wand ormay have an antenna integral with the programmer 28 housing forcommunication. Though not shown in detail, the programmer 28 may includeany suitable user interface, including a screen, buttons, keyboard,touchscreen, speakers, and various other features widely known in theart.

It is unlikely a single patient 10 would have all of the differentsystems implanted as shown in FIG. 1. For purposes of the presentinvention, it is assumed that a patient may have at least twoimplantable systems simultaneously, and it may be beneficial tofacilitate communication between the at least two implantable systems.The mode for communication between two implanted systems may beconducted communication, though other approaches (optical, acoustic,inductive or RF, for example) could be used instead.

FIG. 2 illustrates a block diagram of an implantable medical device. Theillustration indicates various functional blocks within a device 50,including a processing block 52, memory 54, power supply 56,input/output circuitry 58, therapy circuitry 60, and communicationcircuitry 62. The I/O circuitry 58 can be coupled to one or moreelectrodes 64, 66 on the device 50 housing, and may also couple to aheader 68 for attachment to one or more leads 70 having additionalelectrodes 72. The communication circuitry 62 may be coupled to anantenna 74 for radio communication (such as Medradio, ISM, or other RF)and/or may couple via the I/O circuitry 58 to a combination ofelectrodes 64, 66, 72, for conducted communication.

The processing block 52 will generally control operations in the device50 and may include a microprocessor or microcontroller and/or othercircuitry and logic suitable to its purpose. Processing block 52 mayinclude dedicated circuits or logic for device functions such asconverting analog signals to digital data, processing digital signals,detecting events in a biological signal, etc. The memory block mayinclude RAM, ROM, flash and/or other memory circuits for storing deviceparameters, programming code, and data related to the use, status, andhistory of the device 50. The power supply 56 typically includes one toseveral batteries, which may or may not be rechargeable depending on thedevice 50. For rechargeable systems there would additionally be chargingcircuitry for the battery (not shown).

The I/O circuitry 58 may include various switches or multiplexors forselecting inputs and outputs for use. I/O circuitry 58 may also includefiltering circuitry and amplifiers for pre-processing input signals. Insome applications the I/O circuitry will include an H-Bridge tofacilitate high power outputs, though other circuit designs may also beused. Therapy block 60 may include capacitors and charging circuits,modulators, and frequency generators for providing electrical outputs.For devices such as insulin and drug pumps the therapy circuit 60 mayinclude a pump or pump actuator coupled to a delivery system foroutputting therapeutic material, rather than using the I/O circuitry 58as would be typical for systems that generate an electrical therapyoutput.

Communications circuitry 62 may include a frequency generator/oscillatorand mixer for creating output signals to transmit via the antenna 74.Some devices 50 may include a separate ASIC for the communicationscircuitry 62, for example. For devices using an inductive communicationoutput, an inductive coil may be included. Devices may also use opticalor acoustic communication approaches, and suitable circuits,transducers, generators and receivers may be included for these modes ofcommunication as well or instead of those discussed above.

As those skilled in the art will understand, additional circuits may beprovided beyond those shown in FIG. 2. For example, some devices 50 mayinclude a Reed switch or other magnetically reactive element tofacilitate magnet wakeup or reset of the device by a user. Some systemsmay omit one or more blocks, for example, an implantable cardiac monitorcan omit therapy block 60, and an LCP may exclude the header 68 forcoupling to lead 70.

In several embodiments, the present invention is directed toward themanagement and optimization of conducted communication between twoimplanted medical devices. For example, an LCP may communicate with anSICD. The LCP may, for example, provide a detected heartbeat rate to theSICD in order to assist the SICD in making a therapy determination. Inanother example, the SICD may request status from the LCP or may directthe LCP to deliver pacing pulses.

Other combinations of systems may use conducted communication betweenimplants for various reasons. For example, if a patient has both a drugpump and a spinal cord stimulator, the drug pump may communicate to thespinal cord stimulator that it is in need of servicing, such that bothsystems may use their internal annunciating mechanisms to alert thepatient that the drug pump requires service. As integrated systemsdevelop, it may become possible to develop simplified devices that omit,for example, standard telemetry or annunciator circuits, and instead useconducted communication to another implant that includes full telemetryand annunciator circuits. If telemetry and/or annunciator circuits areomitted in one or more devices, the devices may become smaller and powerconsumption may be reduced. Thus conducted communication optimizationmay facilitate development of smaller and/or longer lasting devices inaddition to facilitating inter-device coordination for therapy purposes.

FIGS. 3-5 are schematic diagrams illustrating communications signalsrelative to biological signals. Conducted communication takes placewithin the body, and so it is subject to interference from variousbiological functions. Respiration and the cardiac cycle are twoparticular biological functions of interest, though any other biologicalfunction, cyclic or not, may also be addressed using the methods anddevices herein.

FIG. 3 illustrates an ECG signal at 100, and communications by Device Aat 102 and Device B at 104. The ECG shows a QRS complex (a heartbeat) at106 followed by an interval 108, and another beat at 110. In thisillustration, Device A sends a data packet 112 during the intervalbetween beats 106, 110, and Device B responds with a packet at 114. Thephrase “data packet” is used for convenience and should be understood asgenerically including any type of message/frame structure; no particularstructure, type of data, size or other meaning should be implied.

In FIG. 3, the communication packets are shown as being sent independentof therapy output by either Device A or Device B. FIG. 4 shows anotherscheme in which Device B is configured to embed communications in atherapy output. The ECG is shown at 120, and the therapy output ofDevice B is shown at 124, while the to communications from Device A areshown at 126. The therapy output 124 includes pacing pulses 130 and 136,which trigger beats 132 and 138 respectively on the ECG 120.

A detail view of pacing pulse 130 is shown below, and it is seen at 142that the shape of the pacing pulse 130 includes amplitude modulationembedding a data packet. Other approaches to embedding information in apacing pulse can be used; the illustration is simplified in FIG. 4 sincethe present invention is not limited to any specific manner of embeddingdata.

In the example of FIG. 4, Device A is designed to recognize the data 142embedded in the pacing pulse 130. In this example, Device A respondswith a data packet at 134 following the end of the QRS complex of beat132. In an alternative, Device A could sent data packet 134 and Device Bwould respond with a message embedded in pacing pulse 136. Preferably,the embedded data 142 does not affect the effectiveness of therapy ofthe pacing pulse 130.

The signals for conducted communication are generally intended to haveamplitudes that will not cause cardiac or skeletal muscle contraction,with the exception of the case in which the conducted communication isembedded in a stimulus signal, such as pacing pulse 130 with data 132 inFIG. 4. Typically, the patient should not be aware of the conductedcommunication signal. In FIG. 4, the amplitude, duration and/orfrequency content of the data packet 134 would be selected to avoidstimulating muscle (skeletal or cardiac). Delivery of the data packet134 during the QRS complex 132 could cause Device B to miss the signalor interpret it as part of the QRS complex 132. Therefore, as indicatedat 140, the data packet 134 is intentionally delivered after theconclusion of the QRS complex for beat 132. Meanwhile, the data packet134 must also terminate prior to delivery of the next pacing pulse 136.

While the illustration of FIG. 4 suggests avoidance of the QRS complex,some examples may not include such avoidance. For example, communicationmay be delivered using pulse widths which will allow receiving circuitryto distinguish the QRS complex from a conducted communication signal bythe use of high pass filtering, since the QRS complex generallycomprises signal frequencies below 40 Hertz. Some examples ofoptimization of communication relative to a biological signal such asthe QRS complex are shown in U.S. Provisional Patent Application No.62/134,752, titled COMMUNICATIONS IN A MEDICAL DEVICE SYSTEM WITHTEMPORAL OPTIMIZATION, filed on Mar. 18, 2015, the disclosure of whichis incorporated herein by reference.

FIG. 5 illustrates a scenario in which multiple biological signalsinteract with and potentially impair communication. A signalrepresentative of the impact of respiration is shown at 150, as well asan ECG signal at 152 and communication for Device A at 154 and Device Bat 156. At 160 a combination of communication signals are shown forDevice B with a response from Device A. These communications take placeafter a QRS complex on the ECG. However, a later communication fromDevice B at 162 is not acknowledged at 164 by Device A, possibly due tothe interference of the ECG 152 having a QRS complex at 166. Later, at170, Device B again tries to communicate, however, the respirationsignal at 174 interferes. The respiration signal 174 may represent atemporary change in transthoracic impedance or a motion artifact as thepatient's chest moves, for example.

Other factors may come into play as well. For example, referring to FIG.1, if two electrodes are placed on the ends of the LCP 16 in anorientation that is orthogonal to the electric field of a conductedcommunication that is sent to the LCP, the LCP may not “see” the signal,as the sensing electrodes on the LCP would be at equipotential relativeto the incident electric field. If so, there would be a handful ofpotential mitigations including repositioning the LCP, selecting adifferent pair of electrodes on the LCP (if available) for receiving thesignal, and selecting a different set of electrodes for sending thesignal to the LCP from the SICD, for example. Thus, there are severalfactors that can affect the success of communication attempts.

FIG. 6 illustrates a flow diagram and graphic for an illustrativemethod. In the method of FIG. 6, a testing regimen is put into place toidentify and analyze potential interference sources. In the example, arate estimate is made at 200. For this example, the ECG is theinterference source under test, and so the “rate” is the cardiac beatrate, which can be determined in several ways including, for example,determining the period at which cardiac cycles occur by identifyingR-waves, QRS complexes or other known recurrent parts of the cardiaccycle.

Using the estimated rate from 200, a period is set at 202, in which theperiod is selected to exceed a biological cycle. Here, the period wouldbe chosen as the inverse of the cardiac beat rate plus, optionally, anadditional margin. Optionally, one of the devices involved in the testmay then transmit the testing plan at 204 to the other device(s) in thetest. For example, if the system involved includes an SICD, an LCP, andan external programmer, either the SICD or LCP may provide the rate tothe external programmer (or, if equipped for the task, the externalprogrammer may calculate a rate). Then the external programmer maycommunicate a testing plan to each of the implanted devices at 204, inwhich the period to be used would be sent, along with an instruction toperform a conducted communication test.

In another embodiment, the external programmer can be omitted, and theSICD may provide a plan to the LCP, or the LCP may provide a plan to theSICD. Alternatively, a plan may not need to be conveyed. As shown below,the test will involve delivering a relatively long-durationcommunication output; the receiving device may be equipped to identifythe long-duration communication output as a test mode, and simply waitfor the communication output to terminate. The communication of a plan204 is not necessary but may be helpful for the receiving device of atest communication output to determine that it is not being subjected toan external noise, for example.

Next the test is performed as shown at 206. The test sequence is showngraphically, with the ECG shown at 220, communication outputs of DeviceA shown at 222, and communication output of Device B shown at 224. Inthe test, Device A provides a communication packet at 230, which isacknowledged and responded to by device B at 232. This exchange 230/232may include the optional test plan.

Next, a long-duration communication output is generated by Device A, asshown at 234. As highlighted at 236, the period for the long-durationcommunication output 234 is selected to exceed the length of a cardiaccycle. Optionally, during the long-duration communication pulse output234, a pre-specified pattern of data may be communicated (for example,all “1s”, all “0s” or a repeating 01010101 sequence). Device B listensfor the output 234 and assesses communication metrics which may include,for example, amplitude, relative signal strength indicator (RSSI),signal-to-noise ratio (SNR), slew, frame error or bit error rate (BER),or others. By monitoring over time, the test method can determine howthe ECG affects these communication metrics.

In one embodiment, a mapping can be generated by having the ECG 120captured by one of the devices (either implant or the externalprogrammer, depending on which are available) synchronized to thelong-duration communication output 234. Such a mapping could indicate,for example, if the SNR, RSSI, or BER change depending on the state ofthe ECG. For example, the mapping may indicate if the BER increases orRSSI decreases during the QRS complex of the ECG.

Following the test, results can be reported at 208. For example, DeviceB may send a communication packet 238 to Device A containing datarelating to the observed communication metrics. Such results can beexchanged between two implanted systems or may be sent to an externaldevice (such as a programmer or smartphone) to enable configuration ofsystem communication. A communication strategy may be formulated andredistributed among the devices in the system, if desired. Examples ofstrategy elements may include:

-   -   timing of communication relative to a biological marker such as        a transthoracic impedance peak, QRS complex, R-wave, other        cardiac signal, respiration signal, or received artifact such as        a motion artifact    -   selection of or tiering of communication vectors if multiple        vectors are available    -   communication retry strategies including timing or other changes        to be made with retries    -   modifications to communication signal amplitude, data rate or        other characteristic    -   strategies for handling urgent versus non-urgent communications        with respect to any of the above        Any of these elements may be integrated into a communication        strategy for the system.

FIGS. 7 and 8 are diagrams illustrating communications pulses and testsignals relative to biological signals. Referring first to FIG. 7, therepresented signals include a signal representative of respiration 250,the ECG 252, Device A 254, and Device B 256. Optionally, Device A issuesa communication at 260 requesting a test sequence, and Device B providesa response at 262 acknowledging, approving, and indicating a period touse in the communication. Device A then issues a long-durationcommunication signal at 264, this time being of a duration sufficient tocapture a full respiration cycle, L, plus some margin, delta. Device Bobserves the signal 264 and one or more metrics of the communicationquality and may communicate such information in packet 266 either backto Device A or to an external programmer. A mapping of the receivedcommunication characteristics can be generated using the informationcaptured by Device B, and referencing one or both of the Respirationsignal 250 or ECG 252.

FIG. 8 illustrates an example in which multiple communicationconfigurations can be tested. ECG is shown at 280, and communicationbehavior of Device A at 284 and Device B at 282. Here, Device A sends afirst packet at 286 to request and/or provide parameters for an upcomingtest, and Device B provides acknowledgement and/or parameters at 288. Afirst test is provided at 290, spanning at least one cardiac cycle asillustrated by the ECG 280. Device B acknowledges the end of the firsttest 290 with a response at 292. This acknowledgement 292 may indicate aneed for further testing, if desired. Device A then reconfigures itselfby, for example, selecting a different communication vector, increasingor decreasing signal power or data rate, or adjusting a data format orfrequency for communication. A second test occurs at 294, againoverlapping an entire cardiac cycle as shown in the ECG, and device Bprovides an acknowledgement and test data at 296.

In an alternative, in the arrangement of FIG. 8, the communication 292between tests by Device B may indicate a difficulty receiving the firsttest signal 290, and instructions to reposition Device A or Device B maybe provided. Once the repositioning is completed, then the second testsignal 294 can be generated. Additional intervening data packets may beprovided by one or both of Devices A, B, or an external programmer, tofacilitate retest.

In another alternative, the first test signal 290 may be provided whilea patient is assuming a first posture, for example, the patient may besupine, prone, seated or standing. The second test signal 294 may beprovided with the patient in a different posture. In this manner, thepossible impact on communication success of relative movement and/orreorientation of Device A and Device B due to postural changes can betested.

The system may be configured to use a communication plan that adjusts acommunication configuration to account for posture changes. Toaccommodate a postural plan for communication, one or more implanteddevices may include an accelerometer, piezoelectric device, or otherfeature to allow identification of the patient's posture and toaccommodate any modification of communication that would be taken inresponse. For example, a device may have an accelerometer allowingtracking of the patient's posture between at least first and secondstates. If testing shows that the first state is suited to a firstcommunication configuration, while the second state is suited to asecond communication configuration, the device may switch communicationconfigurations when a detected change from the first state to the secondstate occurs.

FIGS. 9-10 are flow diagrams for illustrative methods. In FIG. 9, asshown at 300, a first test is performed using a first communicationvector, and a second test is performed at 302 using a secondcommunication vector. A report is generated at 304, and thecommunication vector for default use is selected at 306.

FIG. 10 provides another example. Here, an implant procedure is begun at320 for example, for an LCP. One or more communication vectors may betested at 322 using for example an SICD, and the position/orientation ofthe device being implanted can then be adjusted as noted at 324. Forexample, with an LCP, the position of the LCP on the cardiac wall may beadjusted, or the LCP may be rotated. As indicated at 326, with the neworientation a retest may be performed.

For example, in an SICD/LCP combination system, the SICD may beimplanted first. The LCP can be advanced to the right ventricle, butremain un-fixated, or fixated but not released, by the deliverycatheter. A test mode can then be called for the SICD and LCP to checkon communication signals between the SICD/LCP. The two implants may doall the work themselves, or an external programmer may be used to gatherdata from either or both. If desired, an external programmer maycommunicate with the LCP either by conducted communication or by virtueof continued coupling to the delivery catheter (that is, connectedcommunication) may provide a feedback signal (audible or visual, forexample) relating to the communication quality during the implant. Theimplanting physician may adjust the implant position, communicationsensitivity or power level of the LCP prior to fixation or release toensure good communication between the LCP and the SICD. The physicianmay also adjust settings of the SICD. The feedback signal may beprovided in real-time, if desired, that is, as measurement readings aregenerated by one of the implanted devices, those readings can becommunicated to the external programmer and displayed to the user.

In one example, a first implant monitors conducted communication signalsreceived from a second implant using a first pair of electrodes, andgenerates an output communication using a different, possiblyorthogonal, pair of electrodes (for conducted communication) or anantenna or inductive element (for RF or inductive communication) forreceipt and display by an external programmer as measurements are made.FIG. 11 illustrates an example.

In FIG. 11, the conducted communication of Device A is shown at 330, afirst communication channel for device B is shown at 332 as B(1), andmay in this example be conducted communication, a second communicationchannel for Device B is shown at 334 as B(2) and may represent any ofconnected, conducted, RF, optical, acoustic, or inductive communication,and the ECG is shown at 336. As with other examples, Device A and DeviceB optionally exchange messages 340, 342 relating to an impendinglong-duration test pulse 344 that is intended to span a biological cyclesuch as that on the ECG. During the test pulse 344, Device B issues anumber of data packets 348 which may be intended for receipt by anotherimplanted device, by an external programmer, or by Device A, which mayinclude at least two communication channels as well.

In one example, Device B is an LCP having sufficient electrodes to havetwo spatially diverse (such as orthogonal) conducted communicationchannels, while Device A is an SICD having sufficient electrodesdisposed on the torso of the patient to support at least two spatiallydiverse (such as orthogonal) conducted communication channels. In analternative, Device A and Device B can communicate using one mode ofcommunication on a first channel and a second mode of communication on asecond channel. In another example, a higher power communication mode(RF, for example) is used during testing of a lower power communicationmode (conducted communication).

FIGS. 12A-12E show programmer screens for an illustrative method. Thetest method can begin with the programmer screen in FIG. 12(A),instructing the user to press start to begin testing. The testing thentakes place with a “wait” screen illustrated in FIG. 12(B); a status orprogress bar may be provided as well. FIG. 12(C) illustrates a screenindicating that the communication testing was successful, with an exitbutton. FIG. 12(D) shows a screen indicating that the communicationtesting was unsuccessful or marginally successful and communicationability is limited. The user is presented the opportunity to adjust thesystem setup, which may include repositioning one or moredevices/electrodes, or may include changing a setting in one or moredevices either as directed by the user or by following anadjustment/retest protocol. If the user elects, the setup may be leftas-is, with limited inter-device connectivity by selecting the Exitbutton. FIG. 12(E) shows a real-time feedback screen which may indicateto the user the status of the communication link during adjustment ofdevice positioning. For example, if an LCP is being implanted, thesignal strength of conducted communication with another implanted devicecan be displayed on the programmer screen while the implant is takingplace. As an alternative, audible tones or other indicator can beprovided, in place of or in addition to a visible indication on theprogrammer screen.

FIG. 13(A) illustrates a testing setup for implanted systems with anexternal programmer. The external programmer is shown at 350 with a pairof surface electrodes 352, 354, and a telemetry wand 356. An SICD isshown at 360 with a lead extending to electrodes 362, 364, and 366, withthe canister housing the SICD also being an electrode. An LCP is shownat 370, and in the detail view of FIG. 13(B), includes electrodes 372,374, 376, 378. In the configuration shown, the LCP 370 may engage inconducted communication with the surface electrodes 352, 354 of theprogrammer 350, as well as with the housing and lead electrodes 362, 364and 366 of the SICD 360.

Thus, in one example, the LCP could use electrodes 374, 378 as opposingpoles for conducted communication with the surface electrodes 352, 354of the programmer 350, while also using electrodes 372, 376 as opposingpoles for conducted communication with electrode 364 and the housing ofthe SICD, to allow for real-time monitoring of communication qualitiesto the programmer 350 for display to a user. In another example, the LCPcould generate a conducted communication output using electrodes 372,376 for receipt by electrodes 362, 366 of the SICD 360, which in turncan provide real-time data on conducted communication via an antenna(not shown) for RF telemetry to the wand 356 and programmer 350 fordisplay to a user. In yet another example, the LCP may receive conductedcommunication using electrodes 372, 376 from the housing and electrode364 of the SICD, while sending data packets to the SICD using electrodes374, 378 for receipt by electrodes 362, 366. Other configurations andcombinations may also be used.

FIGS. 14-16 are flow diagrams for additional embodiments. In FIG. 14,the testing process begins with Device A telling device B that a test ofconducted communication is going to occur at 400. Next, device A issuesfirst and second communications to device B as indicated at 402. DeviceB receives the first and second communications as indicated at 404.Finally, Device B reports the results of the test to an externalprogrammer, P, as indicated at 406, providing one or more of apreference between the first and second communication attempts and/orcommunication metrics such as signal strength, signal-to-noise ratio orbit error rate, for example. Optionally, P may provide a message to auser/physician to adjust positioning of one or more implanted devices,as shown at 408. Also, optionally, device A may again communicate one ormore data packets to device B to provide real-time feedback to thephysician, at 410. If desired, the entire method may be replaced byblock 410 alone, in which case the real-time feedback may be providedfor each communication test. Though not shown, the programmer P may alsoissue commands to device A to implement a specific configuration ofconducted communication.

In FIG. 15, again, device A may indicate to device B that communicationtesting is to occur, as shown at 420. Next, device A issues first andsecond communication messages, as shown at 422. Finally, device Breceives and analyzes the communications from A, and issues a report toDevice A, as indicated at 424.

In FIG. 16, the initial message from Device A to Device B indicatingthat testing is to take place may be omitted. Instead, the method beginswith Device A communicating to Device B, as shown at 440. Next, device Bprovides an indication that a poor signal was received, as shown at 442.Device A may then reconfigure itself and perform a conductedcommunication test, as shown at 444. In response to the test, device Bprovides a report on the communication quality for the reconfigureddevice A, as shown at 446. If the reconfiguration resulted in betterquality sufficient to meet the system needs, then the reconfigurationcan be stored in Device A and used as a new default configuration.Otherwise, if the communication quality does not improve, Device B mayset an error flag and communicate such an error to Device A, asindicated at 450, in addition to or as an alternative for performing aretest 452.

If desired, one or more therapy or other modes for either of Device A orDevice B may be disabled in conjunction with the error flag at 450. Forexample, if Device A is an SICD, and device B is an LCP, and the SICD isset up to command antitachycardia pacing (ATP) by the LCP usingconducted communication, the setting of the error flag at 450 maysuspend the ability of the SICD to command ATP.

Following are a number of additional illustrative examples which shouldbe viewed as providing additional examples and not as limitations on theinvention.

A first non-limiting example is an implantable medical device comprisingmeans for communicating by conducted communication with at least asecond implantable medical device, in which the means for communicatingmay include the I/O circuitry 58 of FIG. 2 along with the electrodes 64,66 and/or 72, as controlled by the processing circuitry 52 and/orpowered by therapy circuitry 60. The first non-limiting example furtherincludes means for setting the communication module into a continuingreceive mode for analyzing a first signal received from the secondimplantable medical device and a second signal received from the secondimplantable medical device, where the means for setting may comprise theprocessing circuitry 52 using embedded instructions or an instructionset from memory 54 which is configured to perform in the mannerdescribed relative to testing Device B in FIG. 8 (receiving signals 290and 294, for example), and/or the manner described relative to blocks300 and 302 of FIG. 9. This first non-limiting example may furthercomprise means for analyzing the first signal and the second signal asreceived by the means for communicating which may include the I/Ocircuitry 58 of FIG. 2 using dedicated circuitry or operating in concertwith the processing circuitry 52 of FIG. 2 (and memory 54) to generateanalytics such as amplitude, relative signal strength, signal-to-noiseratio, slew, and frame or bit error rate; the means for analyzing mayfurther include input circuitry for analyzing a biological signalincluding, for example, an ECG or EGM analyzer, skeletal or diaphragmmuscle signal analyzer, an accelerometer, a pressure sensor, amicrophone for observing sounds such as heart sounds, a blood analytesensor, or a surrogate of a biological signal such as a thoracicimpedance monitor, etc. Finally the first non-limiting embodiment maycomprise means for generating an output communication indicating aresult of the analysis of the first signal and the second signal,wherein the means for generating an output may comprise the processingcircuitry 52 of FIG. 2 making use of one of conducted communicationcircuitry including the I/O circuitry 58 and electrodes 64, 66, and/or72, or the communication circuitry 62 and antenna 74, which may performas shown in block 208 of FIG. 6, or block 304 of FIG. 9, or block 406 ofFIG. 14, or block 424 of FIG. 15, and associated text.

A second non-limiting example takes the form of an implantable medicaldevice comprising means for communicating by conducted communicationwith at least a second implantable medical device in which the means forcommunicating may include the I/O circuitry 58 of FIG. 2, as controlledby the processing circuitry 52 and/or powered by therapy circuitry 60where the processing circuitry may use embedded instructions orinstructions stored in memory 54. The second non-limiting examplefurther includes at least first, second and third electrodes (such aselectrodes 64, 66 and/or one or more of the electrodes at 72),configured for conducted communication with the second implantablemedical device such that at least first and second conductedcommunication vectors are available for use by the communication means.The second non-limiting example further includes means for setting themeans for communicating to a continuing transmit mode for using thefirst conducted communication vector to generate an output, and thenusing the second conducted communication vector to generate an output,the means for setting including at least the I/O circuitry 58 of FIG. 2,as controlled by the processing circuitry 52 and/or powered by therapycircuitry 60, where the processing circuitry may use embeddedinstructions or instructions stored in memory 54, which may perform asshown in FIG. 8 (with communications 290 and 294) or in accordance withblocks 300 and 302 of FIG. 9, or block 402 of FIG. 14, or block 422 ofFIG. 15, as well as associated text. The second non-limiting examplefurther includes means for determining, from information provided backto the implantable medical device, which, if any, of the first conductedcommunication vector and second conductive communication vector is to beused for delivering conducted communication messages to the secondimplantable medical device, which means may include the processingcircuitry 52 and/or powered by therapy circuitry 60, where theprocessing circuitry may use embedded instructions or instructionsstored in memory 54, which may perform as noted at block 304 of FIG. 9,or blocks 404/406 of FIG. 14, or block 424 of FIG. 15, as well asassociated text. Finally the second non-limiting embodiment may includemeans for setting a default conducted communication vector for use bythe means for communicating, the processing circuitry 52 and/or poweredby therapy circuitry 60, where the processing circuitry may use embeddedinstructions or instructions stored in memory 54 and may perform thesteps as noted by block 306 of FIG. 9 and associated text.

Those skilled in the art will recognize that the present disclosure maybe manifested in a variety of forms other than the specific examplesdescribed and contemplated herein. For instance, as described herein,various examples include one or more modules described as performingvarious functions. However, other examples may include additionalmodules that split the described functions up over more modules thanthat described herein. Additionally, other examples may consolidate thedescribed functions into fewer modules. Accordingly, departure in formand detail may be made without departing from the scope and spirit ofthe present disclosure as described in the appended claims.

What is claimed is:
 1. A method of configuring communication between implantable medical devices comprising: in a first medical device having a plurality of electrodes configured for outputting a conducted signal, generating a first conducted signal using a selected pair of electrodes; in a second medical device, receiving and analyzing the first conducted signal; in the second medical device, communicating a second signal related to an outcome of the analysis of the first conducted signal while the first conducted signal is being received.
 2. A method as in claim 1 further comprising receiving the second signal in the first medical device while the first conducted signal is still being generated.
 3. The method of claim 2 wherein the second signal is a conducted signal received by the first medical device using a different pair of electrodes than the pair used for generating the first conducted signal.
 4. The method of claim 1 further comprising receiving the second signal with an external device configured for communication with at least one of the first medical device and the second medical device.
 5. The method of claim 4 wherein: the second medical device analyzes the first conducted signal and calculates communication metrics of the first conducted signal as received by the second medical device; the second signal encodes data related to the communication metrics of the first conducted signal as received by the second medical device; and the external device is configured to provide real time feedback to a user related to the communication metrics.
 6. The method of claim 5 wherein the external device provides real time feedback in the form of a message indicating adjustment of positioning of at least one of the first or second medical devices is desired.
 7. The method of claim 1 wherein the first and second medical devices are each leadless cardiac pacemakers.
 8. The method of claim 1 wherein the first medical device is a leadless cardiac pacemaker, and the second medical device is an implantable cardioverter defibrillator.
 9. A method of configuring communication between implantable medical devices during an implantation procedure of a first medical device in a patient in whom a second medical device is already implanted, the method comprising: during an implantation procedure for the first medical device, testing communication between the first medical device and the second medical device; determining that communication is suboptimal; and in response to determining that communication is suboptimal, adjusting an orientation of the first medical device.
 10. The method of claim 9 wherein at least one of the first medical device and the second medical device is configured for communication with an external programmer, the method further comprising obtaining a feedback signal from the external programmer which indicates in real time a quality of a communication link between the first medical device and the second medical device.
 11. The method of claim 9 wherein the first medical device is a leadless cardiac pacemaker and the second medical device is an implantable cardioverter defibrillator.
 12. The method of claim 9 wherein the first medical device is a leadless cardiac pacemaker (LCP) which is implanted by advancing an implantation catheter to a desired location and then securing the LCP at the desired location and decoupling the implantation catheter from the LCP, wherein the step of testing communication is performed while the LCP is coupled to the implantation catheter and before the LCP is secured at the desired location.
 13. The method of claim 9 wherein the step of testing communication between the first medical device and the second medical device comprises: the first medical device generating a first conducted signal using a selected pair of electrodes; the second medical device receiving the first conducted signal; the second medical device calculating communication metrics based on the first conducted signal; and the second medical device communicating the calculated communication metrics to an external programmer.
 14. The method of claim 9 wherein the step of testing communication between the first medical device and the second medical device comprises: generating a first conducted signal from the first medical device to the second medical device comprising an output pattern for a selected period; and receiving the conducted signal by the second medical device and calculating a first communication metric of the first conducted signal as received; wherein the selected period exceeds an expected or detected length of a recurring biological cycle.
 15. The method of claim 9 wherein the first and second medical devices are each leadless cardiac pacemakers.
 16. A method of operation in an implantable medical device system comprising an external programmer and first implantable medical device and a second implantable medical device, the method being configured for communication quality monitoring during a procedure to implant the second medical device while the first medical device is already implanted, the method comprising: the first medical device generating a communication test signal prior to completion of placement of the second medical device during the procedure to implant the second medical device; the second medical device receiving and analyzing the communication test signal from the first medical device; the second medical device generating an output indicating a quality of the communication test signal as received; the programmer providing an indication to a physician performing the implantation procedure related to the quality of the communication test signal as received by the second medical device.
 17. The method of claim 16 wherein the step of the second medical device generating an output indicating a quality of the communication test signal comprises the second medical device communicating to the programmer in real time, such that the step of the programmer providing an indication is performed in real time.
 18. The method of claim 16 wherein the step of the second medical device generating an output indicating a quality of the communication test signal comprises the second medical device communicating back to the first medical device and the first medical device communicating to the programmer to facilitate the programmer providing the indication to the physician.
 19. The method of claim 16 wherein the first and second medical devices are each leadless cardiac pacemakers.
 20. The method of claim 16 wherein the first medical device is a subcutaneous implantable cardioverter defibrillator and the second medical device is a leadless cardiac pacemaker. 